No Response From Transfer Case Control Module

NO RESPONSE FROM TRANSFER CASE CONTROL MODULE

No Response From Transfer Case Control Module:

POSSIBLE CAUSES
- (Z905) Ground circuit open
- (A34) Fused B+ circuit open
- (D25) PCI BUS circuit open
- Transfer case control module

Diagnostic Test

1. ESTABLISH COMMUNICATIONS WITH THE INSTRUMENT CLUSTER (MIC)
Turn the ignition on.

NOTE: Ensure there is PCI bus communication with other modules. If not, refer to the PCI Bus Communication Failure symptom and repair as necessary.

With the DRB, attempt to communicate with the Instrument Cluster.

Q: Was the DRB able to I/D or communicate with the Cluster?

YES: Go To 2
NO: Perform TRANSFER CASE VERIFICATION TEST. Transfer Case Verification Test

2. (Z905) GROUND CIRCUIT OPEN




Turn the ignition off.
Disconnect the Transfer Case Control Module harness connectors.
Using a 12-volt test light connected to 12-volts, probe each (Z905) ground circuit.

Q: Is the test light illuminated for each circuit?

YES: Go To 3
NO: Repair the (Z905) Ground circuit for an open. Perform TRANSFER CASE VERIFICATION TEST. Transfer Case Verification Test

3. (A34) FUSED B+ CIRCUIT OPEN




Using a 12-volt test light connected to ground, probe the (A34) Fused B+ circuit.

Q: Is the test light illuminated?

YES: Go To 4
NO: Repair the (A34) Fused B+ circuit for an open. Perform TRANSFER CASE VERIFICATION TEST. Transfer Case Verification Test

4. (D25) PCI BUS CIRCUIT OPEN




Turn the ignition on.
Use Scope input cable CH7058, Cable to Probe adapter CH7062, and the red and black test probes.
Connect the scope input cable to the channel one connector on the DRB.
Attach the red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIII(R) select Pep Module Tools.
Select lab scope.
Select Live Data.
Select 12 volt square wave.
Press F2 for Scope.
Press F2 and use the down arrow to set voltage range to 20 volts.
Press F2 again when complete.
Connect the Black lead to the chassis ground.
Connect the Red lead to the PCI Bus circuit in the TCCM connector.
Observe the voltage display on the DRB Lab Scope.

Q: Does the voltage pulse from 0 to approximately 7.5 volts?

YES: Replace the Transfer Case Control Module. Perform TRANSFER CASE VERIFICATION TEST. Transfer Case Verification Test
NO: Repair the (D25) PCI Bus circuit for an open. Perform TRANSFER CASE VERIFICATION TEST. Transfer Case Verification Test